1. Field of the Invention
This invention relates to a portable electronic device such as a handy terminal, and more particularly to a portable electronic device which has the function of automatically turning off a power source after a lapse of a predetermined time from the last keyboard operation, and which performs a resuming function of maintaining data which was processed in a program memory, and then enabling a user to resume the processing of the data when the power source is turned on by the user.
2. Description of the Related Art
In recent years, portable electronic devices which driven by batteries have been developed, and have been utilized in the fields of distribution, finance, traffic, and the like. The battery used in these devices must be small and light since the devices would otherwise become large and heavy. The smaller the battery, the less the power storage available. To operate the battery-driven devices as long as possible, the devices must have a function for saving power. This is why hand-held calculators, for example, have an automatic power-off function.
Without an automatic power-off function, a device will waste power if the user forgets to turn off the power switch or turns on the power switch unnecessarily. To save power, the user may turn off the power switch upon finishing a data processing. Every time he or she turns off the switch, the data processed is erased and can no longer be processed.